Terahertz (THz) waves are generally referred to the spectrum from 0.1 to 10THz (or more strictly with lower bound limited to be 0.3THz). THz waves have unique properties due to its special position in the electromagnetic (EM) spectrum, which lies in the gap between the electronics and photonics. So both the technologies borrowed from the electronics and the photonics play important roles in this band. In recent years, imaging and sensing with EM radiation in Terahertz band has aroused considerable interests, and is found to be promising for plenty of applications, such as personal screening for security, surrounding surveillance for safety, non-contact and non-destructive materials testing, biomedical analysis and diagnostics, and so on. Design and realization of imaging systems at THz band with high performance is dependent on variety of key parameters such as spatial resolution, sensitivity, target contrast, target identification, and so on. This paper describes and summarizes some recent progress on THz active imaging methods and technologies in the Key Laboratory of Electromagnetic Radiation and Sensing Technology, Chinese Academy of Sciences (CAS EMRST), both in theoretical and system engineering aspects. The synthesized aperture concept was extended to terahertz band with combination of novel beam-scanning mechanism. Approaches to conduct terahertz imaging with sparse information were also introduced for the aim of system complexity and cost reductions. Terahertz frequency modulated continuous wave (FMCW) transceiver with quick modulation rate was designed and developed, which make it possible to realize fast coherent measurement and real-time 3D imaging in THz band, and has potential applications for security screen and fast biomedical analysis.
© 2016 Optical Society of AmericaPDF Article